This invention relates to highly electron-conductive composition showing excellent thermal stability or quite small evaporation loss even at a high temperature near melting point. Hereinbefore, it has been known that multiple oxides of the general formula (L.sub.1-x Mx)QO.sub.3 , such as La.sub. 0.9 Ca.sub. 0.1 CrO.sub.3, Nd.sub. 0.77 Sr.sub. 0.23 CoO.sub.3 and PrCoO.sub.3, show electron-conductivity at from ordinary temperatures to high temperatures. These muliple oxides have high melting points of at least 1500.degree. C. Recently, they have been gradually utilized as electrode materials for fuel cells and MHD transformers. However, the electrical and physical properties of these known multiple oxides are deteriorated at high temperature near their melting points, therefore, it is a serious problem that their life is short. Such a disadvantage is caused by evaporation of components composing the multiple oxides, and one of the main evaporating components is oxide of Q in the general formula (L.sub.1-x Mx)QO.sub.3. When a part of the components of multiple oxide is evaporated in such a manner, the crystal structures of the multiple oxides themselves are changed to cause shortening of their life. When the above Q is evaporated almost 1% by weight of (L.sub.1-x Mx)QO.sub.3, excess oxides of (L.sub.1-x Mx) are swelled in accordance with their hydration under leaving them alone at ordinary temperature, and, finally, decomposed spontaneously. An object of this invention is to overcome the problems and disadvantages of the known multiple oxides. A further object of this invention is to provide novel highly electron-conductive composition which is scarcely evaporated even at high temperature near the melting point.
Other objects and advantages of this invention will become apparent hereinafter.